Computer model of cardiac potential distribution in an infinite medium and on the human torso during ventricular activation.

The cardiac electrical field produced by the depolarization of the ventricles of a human heart was simulated with a computer, and the results were presented as isopotential maps. Computations were first done with the heart theoretically immersed in an infinite homogeneous medium and then with it located inside a homogeneous human torso. The principal feature of the model was that only the cardiac regions actually engaged in the depolarization generated an electrical current. Owing to their thinness, these regions could be reduced to the surfaces separating active and inactive cardiac zones at a definite instant. The surfaces used were the isochronal surfaces published by Durrer et al. for the pattern of ventricular excitation in a human heart. The assumption was made that the current flowed perpendicularly and with the same strength at each point on the surfaces. The isopotential maps were drawn on a cylindrical surface surrounding the heart and on the torso. The simulated maps were described in connection with the cardiac activation and compared with experimental maps.